Balance and Postural Outcomes of Vibration Therapies in Parkinson's Disease: Protocol for a Systematic Review and Meta-Analysis.

Balance impairment is a major motor symptom of Parkinson's disease (PD), leading to falls, reduced mobility, and lower quality of life. Despite advances in pharmacological and rehabilitation approaches, postural instability often persists, requiring effective adjunctive interventions. Vibration therapy (VT) is a non-invasive, drug-free method that may enhance neuromuscular and balance control. However, evidence remains inconsistent due to methodological heterogeneity and small samples. This protocol describes a systematic review and meta-analysis designed to evaluate the effects of VT on balance in individuals with PD. Following PRISMA-P 2015 and Cochrane Handbook guidelines, the protocol is registered in PROSPERO (CRD420251124173). Searches will include PubMed, EMBASE, MEDLINE, Web of Science, and Cochrane Library for English-language, peer-reviewed randomized and non-randomized controlled studies comparing VT (WBV, FMV, or SRT) with control interventions. Risk of bias will be assessed using RoB 2 and ROBINS-I tools. A 3-level random-effects meta-analysis will address within-study dependencies, followed by subgroup and meta-regression analyses. Certainty of evidence will be rated using GRADEpro. This review will synthesize available evidence on the effects of vibration therapy on balance and postural outcomes in individuals with Parkinson's disease. Pooled effect sizes will be estimated, and potential sources of heterogeneity will be examined through predefined subgroup analyses and multilevel meta-regression based on clinical and intervention-related factors. This review will clarify the therapeutic potential of VT for balance in PD and guide evidence-based rehabilitation strategies.Systematic review registration: PROSPERO CRD420251124173.